openssl/doc/man3/EVP_PKEY_sign.pod
Dr. Matthias St. Pierre fc5ecaddd0 man: harmonize the various formulations in the HISTORY sections
While stereotyped repetitions are frowned upon in literature, they
serve a useful purpose in manual pages, because it is easier for
the user to find certain information if it is always presented in
the same way. For that reason, this commit harmonizes the varying
formulations in the HISTORY section about which functions, flags,
etc. were added in which OpenSSL version.

It also attempts to make the pod files more grep friendly by
avoiding to insert line breaks between the symbol names and the
corresponding version number in which they were introduced
(wherever possible). Some punctuation and typographical errors
were fixed on the way.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7854)
2018-12-15 22:27:26 +01:00

116 lines
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=pod
=head1 NAME
EVP_PKEY_sign_init, EVP_PKEY_sign - sign using a public key algorithm
=head1 SYNOPSIS
#include <openssl/evp.h>
int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
unsigned char *sig, size_t *siglen,
const unsigned char *tbs, size_t tbslen);
=head1 DESCRIPTION
The EVP_PKEY_sign_init() function initializes a public key algorithm
context using key B<pkey> for a signing operation.
The EVP_PKEY_sign() function performs a public key signing operation
using B<ctx>. The data to be signed is specified using the B<tbs> and
B<tbslen> parameters. If B<sig> is B<NULL> then the maximum size of the output
buffer is written to the B<siglen> parameter. If B<sig> is not B<NULL> then
before the call the B<siglen> parameter should contain the length of the
B<sig> buffer, if the call is successful the signature is written to
B<sig> and the amount of data written to B<siglen>.
=head1 NOTES
EVP_PKEY_sign() does not hash the data to be signed, and therefore is
normally used to sign digests. For signing arbitrary messages, see the
L<EVP_DigestSignInit(3)> and
L<EVP_SignInit(3)> signing interfaces instead.
After the call to EVP_PKEY_sign_init() algorithm specific control
operations can be performed to set any appropriate parameters for the
operation (see L<EVP_PKEY_CTX_ctrl(3)>).
The function EVP_PKEY_sign() can be called more than once on the same
context if several operations are performed using the same parameters.
=head1 RETURN VALUES
EVP_PKEY_sign_init() and EVP_PKEY_sign() return 1 for success and 0
or a negative value for failure. In particular a return value of -2
indicates the operation is not supported by the public key algorithm.
=head1 EXAMPLE
Sign data using RSA with PKCS#1 padding and SHA256 digest:
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
/* md is a SHA-256 digest in this example. */
unsigned char *md, *sig;
size_t mdlen = 32, siglen;
EVP_PKEY *signing_key;
/*
* NB: assumes signing_key and md are set up before the next
* step. signing_key must be an RSA private key and md must
* point to the SHA-256 digest to be signed.
*/
ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_sign_init(ctx) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
/* Error */
/* Determine buffer length */
if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
/* Error */
sig = OPENSSL_malloc(siglen);
if (!sig)
/* malloc failure */
if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
/* Error */
/* Signature is siglen bytes written to buffer sig */
=head1 SEE ALSO
L<EVP_PKEY_CTX_new(3)>,
L<EVP_PKEY_CTX_ctrl(3)>,
L<EVP_PKEY_encrypt(3)>,
L<EVP_PKEY_decrypt(3)>,
L<EVP_PKEY_verify(3)>,
L<EVP_PKEY_verify_recover(3)>,
L<EVP_PKEY_derive(3)>
=head1 HISTORY
These functions were added in OpenSSL 1.0.0.
=head1 COPYRIGHT
Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
=cut